The present invention relates to an image pickup system for transmitting image information, particularly to a video input apparatus and an image pickup system including the video input apparatus preferably used to a video telephone conference system for transferring images, voices and other multimedia information between remote points through a general public telephone network.
A conventional image pickup apparatus is constituted so as to mount a zooming or auto-focusing camera unit on a pan tilting head such as a tripod head, process a picked-up video signal by an image processing unit set in the camera unit, output the processed video signal in accordance with an NTSC signal format, and display the signal on a monitor or transmit the signal to a host terminal of a personal computer or the like.
Therefore, the above conventional pickup apparatus has problems that the entire camera unit including the image processing unit must be replaced in order to improve, for example, the resolution of a video signal and moreover, and the entire apparatus including the camera unit must be replaced in order to change the format of a video signal to be output from the NTSC format to, for example, the interface of IEEE 1394.
Moreover, because a computer and its communication art have advanced in recent years, the foundation for handling an image on a computer has spread and a video camera has been used as its main video input means. For example, in the case of a video telephone conference system, documents such as a material made by a speaker or used in the conference are input and transmitted to a remote other party.
Furthermore, because the number of video telephone conference systems using an ISDN line has increased, the structure and the terminal of an AV (Audio Visual) system of N-ISDN is recommended as ITU-T H. 320. Furthermore, by spreading the network of ISDN up to general public telephone lines, recommendation of a multimedia terminal for a low-bit-rate video telephone is advanced as H. 324.
A video camera for capturing an image is typically listed as a multimedia terminal of a video telephone conference system or a component of the system. Some of the video cameras are respectively mounted on a tripod head which can be rotated in the horizontal or vertical direction in accordance with an external control signal. Moreover, there is an integral-type video camera constituted by integrating the video camera with the tripod head.
By using the video camera and tripod head, a video telephone conference system makes it possible to control a remote video camera such as the video camera of a station on the other end of the line from a remote place. Moreover, some of the camera systems used for video telephone conference systems can be respectively divided into a camera head section including a CCD, TG (timing generator), AGC (auto gain control) circuit and a signal processing board section including an A-D (analog-to-digital) converter, signal processing section, and image and voice CODEC (encoder-decoder) section. By using the above type of camera system, it is possible to directly CODEC-process a digital image signal without converting the image signal into a video signal and moreover realize various camera systems by being available the signal processing board section in common and replacing only the camera head section.
Moreover, by making a tripod head section separable, it is possible to constitute various types of camera systems in accordance with the type of a CCD, difference of the single focus point or zoom of a lens, or presence or absence of a tripod head section. FIG. 76 shows a full view of a camera system in which a camera head ection 5100 mounting a zoom lens with a tripod head ection 5200.